I can’t quite put my finger on why British TV often surpasses anything produced here.

Maybe it just seems that way to a jaded viewer, but I do know that “Thorne,” airing Tuesday and Wednesday nights on Encore, is yet another in a distinguished line of smartly written, acted and, above all, atmospheric English dramas.

Unless you have access to the UK’s Sky 1, which first aired “Thorne” in 2010, the two-part series — based on Mark Billingham’s best-selling novels “Sleepyhead” and “Scaredy Cat” — will be a new viewing experience.

And I can tell you that “Thorne: Sleepyhead,” which airs first on Tuesday night, has enough twists, turns, red herrings and multi-layered narrative to keep you couch-bound for its entire two hours.

David Morrissey stars as world-weary Inspector Detective Tom Thorne, famous in his London precinct for cracking a case 15 years before (in which a serial-killer father murdered his three young daughters, who were discovered by Thorne). That case left him emotionally traumatized, and reverberates, even now, as he hunts down a serial killer stalking young women who are drugged, paralyzed and left for dead.

Except one.

Her name is Alison Willetts (Sara Lloyd-Gregory) and she’s survived her ordeal — “survived” being a relative term here since Alison, who was dropped at the hospital by persons unknown, was left paralyzed and on a respirator. Internally, she’s perfectly coherent — we hear her thoughts in haunting voiceover — but outwardly she has what’s called “locked-in syndrome” and can only communicate, agonizingly so, by blinking her eyes or via an ocular-tracking device.

While Thorne plunges deeper into the case, he starts to fall for the doctor (Natascha McElhone) who’s treating Alison — which doesn’t help his case, since more young women fall victim to the killer who, Thorne theorizes, doesn’t really want to kill his victims but to “save” them in a psychotic, God-complex sort of way.

Maybe I’m just extremely gullible, but I had at least three different suspects convicted before the actual “Sleepyhead” killer is unmasked — testimony to Dudi Appleton and Jim Keeble’s scintillating writing and to the direction of Stephen Hopkins, who also directed several episodes of “24” (so he knows a thing or two about suspense).